This is the German edition of Sasha Grey's The Janus Chamber. The "H" might be modified from the original font.

I would say (the old version of) Agenda (also here) with an alternate |U|, but I haven’t found how to confirm if such alternate exists.

Curiously, the English version uses a stemless |U|.

Thank you, @Riccardo Sartori. Agenda seems like a perfect match. The German edition of the first volume in the series, The Juliette Society, uses a stemless "U", as well, while the German edition of The Janus Chamber uses an U with stem. Maybe the designer has added the stem for reasons of readability or to create a specific look and feel. Anyway, thank you! That was a great help.